The aforementioned related application discloses an alternative approach to my earlier patented dispensing pumps mentioned therein, in the form of a trigger actuated dispenser of the pressure accumulating type in which the discharge is opened upon an accumulation of pump pressure above a predetermined minimum.
This invention relates to a dispenser of the general aforementioned type which by a simple modification is made to continue to discharge product under pressure even after the pumping action on the pump plunger has been completed.
The trigger actuated dispenser disclosed in my aforementioned related application includes a spring biased pump plunger having an inlet check valve and forming a pump piston acting within a pump cylinder defined by an accumulator element in the form of a hollow sleeve having an annular discharge valve thereon. The piston and accumulator define a variable volume pressure pump chamber during plunger reciprocation, and a blind socket formed at one end of the pump body defines with the accumulator an enclosed variable volume pressure accumulation chamber of larger diameter relative to the pump chamber and in direct and open communication therewith. A return spring acts between the plunger and the accumulator for urging the discharge valve closed, and the spring likewise resiliently urges the plunger outwardly of the pump chamber into a container vent closed and sealed position. During the plunger compression stroke the pressure within the accumulation chamber increases which effects a shifting away of the accumulator from the blind socket end of the pump body whereupon the discharge passage opens for effecting a discharge of product under pressure from the pump chamber. The discharge continues until the plunger is released and the reduced pressure in the pump chamber is again overcome by the stored spring force by closing the discharge as the accumulator returns to its original position. And, a sustained discharge of product at regulated pressure is made possible.
And, in my U.S. Pat. No. 4,402,432, a finger actuated dispensing pump includes a stationary valve-controlled piston and a spring-biased sleeve-like accumulator having an annular discharge valve thereon. The piston and accumulator define a variable volume pressure pump chamber during plunger reciprocation, and a blind socket formed at the underside of the plunger head defines with the accumulator an enclosed variable volume pressure accumulation chamber of larger diameter relative to the pump chamber and in direct and open communication therewith. A return spring acts between the pump body and the accumulator for urging the discharge valve closed, and the spring resiliently urges the accumulator into a container vent closed and sealed position. Dispensing takes place under pressure in a manner similar to that described above for my trigger actuated dispenser, and is likewise capable of effecting a sustained discharge. However, at any point where the actuator (trigger, etc.) is released, the accumulator is immediately returned to the discharge closed position because of the chamber pressure drop below operating pressure.
For some dispensing operations, it is desirable to dispense product in a continuous stream or spray even during the recovery movement of the pump plunger. Various approaches have been taken to effect such continuous discharge, as for example those disclosed in U.S. Pat. Nos. 4,079,865, 4,109,832, 4,146,155, 4,174,056 and 4,222,501. However, each of these dispensers requires many parts and rather complicated arrangements which limit the effectiveness during assembly and operation. In each of these continuous sprayers, the pump cylinder is separate from the accumulator or storage compartment piston, which thereby gives rise to a specific dispenser operation and function requiring, for example, separate plunger and accumulator return springs or other resilient means. Moreover, the plunger and accumulator are incapable of operating together as a unit in these prior dispensers during such occasions as may be needed to manually, rather than merely resiliently, overcome the hydraulic pressure in the accumulation chamber to assure proper discharge.